High blood pressure can occur in pregnancy in two forms. It may be a preexisting condition, called chronic hypertension, or it can develop during pregnancy--a condition known as gestational hypertension. It is also called toxemia or preeclampsia and occurs most often in young women with a first pregnancy.
AC relays. AC relays are manufactured similar to their DC counterparts. If AC current is applied to a DC relay, the relay will pulse at the frequency of the AC current. To overcome this problem, the core is equipped with a shading ring on one-half of the core (Photo 2).
Impulse Relays Impulse relays are a form of latching relay that transfers the contacts with each pulse. Many impulse relays are made up of a magnetic latch relay and a solid state steering circuit that, upon application of power, determines which position the relay is in and energizes the opposite coil. The contacts transfer and hold that position when power is removed.